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Hemi MDS major problems

I have a 2006 Dodge Ram 4x4 with the Hemi MDS engine. I have had too many problems with this truck to list but now I have a major problem. Got the truck back from the dealer after the last repair and parked it. Went out and started it about a week later and a very loud and noise started banging and popping from the left side of engine. Shut it down and restarted it, same thing. I just let it rattle and bang but the warmer the engine got the quieter it got. Engine was also missing. When the engine warmed all the way up the missing and noise went away. Matter of fact sitting at a stop light you can't even tell the engine is running. When its cold the engine misses and has lifter noise and pops every now and then. There is to me an excess of watter coming out of the tail pipe and where the pipe hooks on. Check engine light is on. Dealer mechanic said something on the MDS broke in the number one cylinder valves and would cost $1.200.00 to fix. There is a very small coolant leak coming from that same corner of the engine but they say they can't find it. I believe I have a cracked head or blown gasket. Any help out there? I'm 72 years old and can't work on vehicles anymore. Truck has 86000 miles on it and was to be my last retirement truck.

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It only does it when the engine is cold. They spent 3 hours trying to align it and never did get it right. Sad thing is my warranty ran out the day before. I spent $2.100.00 on 2 warranties and $1.600.00 for 16 trips to have something repaired. Cost me $100.00 deductable each visit. Seemed like every time I took it to them something else went wrong within a day or two after bringing it home.

It seems hard to believe that there is something that horribly wrong if the noise goes away once it warms up. HEMIs are pretty reliable I think, though they are known for dropping valves in that generation of engine. However, this isn't a noise that I could imagine would get better when the engine warms up, much less completely go away. It would be useful to know what malfunction codes are stored as well. Can you get them read and post them? You may be able to try the "key trick" to get the codes--without starting the truck, turn the ignition on-off-on-off-on quickly and leave it on. The codes will be displayed on the odometer or dash display or blink out on the check engine light. This has worked with Chrysler vehicles since the early 90s.

One thing about the Chrysler MDS system is that it's very important to use the correct weight of oil, as the system is oil-operated. I think your vehicle calls for 5W-20 oil. If you have been using anything heavier, especially if it's getting cold where you live, this can cause problems. What does the oil cap say, and what have you been using? If you've been using the wrong weight of oil, change it immediately and see if it helps. The dealer or shop could easily have put the wrong oil in it too. Mine likes Amsoil synthetic 5W-20 very well.

I had the code ran several times and it says missfire number one cylinder. They kill the check engine light and it comes back on the next time I use the truck. I had the oil changed and they used 5w20. I changed dealerships. They were the people that told me what they think is wrong. The lower the oil pressure gets the quieter the engine get until there is no noise at all except for normal. I do believe the dealer was using 10W30 but will have to call and hope they tell me the truth. I even thought about using 0W20 oil and see what happens.

So the gist of it is they think the system that disables 4 of the 8 cylinders is malfunctioning and causing the miss and the noise? Probably a good next step would be to have a compression test done on the engine when cold and missing and warmed up and behaving and see what the numbers are. Since MDS works in part by disabling the valves on 4 of the cylinders, a compression test that is poor would indicate a valve problem, while one that is consistent both cold and warm (in theory) would indicate a problem with the MDS engaging on that cylinder when it shouldn't. You say the engine gets quiet when the oil pressure drops--can you tell me what the oil pressure is when the problem is occurring and what it is when it goes away? Let me know if you need explained how to get to the readout for the oil pressure on the "EVIC" (the information display)

Hemis are notorious for a lifter tick, but typically it doesn't affect the operation of the engine. They are not known for having head gasket problems, but of course anything is possible.

It may be worth getting a second opinion from another dealer or shop familiar with the hemi. But if the roller tappet that disables the MDS is malfunctioning, the price you were quoted doesn't sound unreasonable to repair it.

Don't know what the actual PSI is but the gauge goes all the way over when cold and just above center when hot. Your idea of the compression check is a great one. I will have that done. If that is the problem I will try to find a way to disable MDS. I hate the thought of the great hemi being changed that way anyway! I suspect the compression will tell a lot. Thank you, Rosie

Rosie, if you have the "EVIC" --the blue display between the speedometer and tachometer--and steering wheel controls, press the inner most right hand control (not the radio volume one) up and cycle through until you see either "Vehicle Information", "Status OK" , or "Warnings" Now press the left most control on the steering wheel up until you get oil pressure--should just be one press. Subsequent presses will give you oil temperature and tire pressures.

There is also a "hidden" menu that will give you coolant temp, battery voltage, a digital speedometer, oil pressure, and a lot of other adjustments--you can access it by pressing the two inner most buttons on the steering wheel down and holding them there for about 10 seconds until the display changes.

I don't think the oil pressure gauge should be pegged on a cold start at idle. Mine typically has about 58-60 PSI indicated on the gauge when first started in cold weather. Once the oil warms, I get about 18-25 PSI at idle depending on how hot the oil is.

If your oil pressure is extremely high due to some kind of malfunction--and something as simple as a bad oil filter can cause this, it could cause problems.